Improvement in processes and apparatus for the manufacture of iron and steel



J. W. MIDDLETON.

Improvement n Process and Apparatus for the Manufacture of Iron and Steel.

plm-129,243..

Patented luly 16,1872.

WITNESSES':

, INVENTOR.

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UNITED STATEs t PATENT OFFICE.

JOHN w. MIDDLEToN, or PHILADELPHIA, rENNsYLvAN'IA.

IMPROVEMENT IN PROCESSES AND APPARATUS FOR THE MANUFACTURE OF IRON AND STEEL.

Specification forming part of Letters Patent No. 129,243, dated July 16, 1872,

Specification describing certain Improvements in the Process of Producing Iron and Steel directly from the Ore, and in the Apparatus therefor, invented by JOHN W. MIDDLE- TON, of the city of Philadelphia, in the State of Pennsylvania.

The rst part of my invention relates to the process, hereinafter described, whereby either malleable iron, steel, or cast-iron can be produced with certainty and facility directly from the ore, either in a small or large way, or in quantities from one to one hundred tons daily, at the will of the manager, the object of this part of my invention being to greatly lessen the cost of producing malleable iron and steel, and to enable the chemist in his laboratory, or

the owners of mines who cannot command the second part of my invention relates to the peculiar construction and arrangement of the hearth of a furnace-stack, kiln, or a curbwall on any open plane in its relation to the blast, the surrounding wall or curb, and any suitable run-out opening or channel for the passage of the fluid metal and slag from the same, substantially as hereinafter described, whereby either the malleable iron, steel, or cast-iron produced by such reducing apparatus may be immediately disposed of in making castings, or run either into pigs as cast-iron, or, if malleable iron, into any suitable gravity or chemically-refining vessel, or, if steel, into ingots, as may be desired. The third part of my invention relates to the peculiar construction, as hereinafter described and set forth, of the water-tuyeres for an intensified or other hot blast in ore-reducing furnaces, whereby a more copious and effective supply of cool water can be maintained at theire-end of the said tuyere, and, consequently, its durability proportionately increased.

Figure l is a vertical central section, representin g an inclined hearth with steps or ledges and tuyere openings for the entrance of slightly-inclined blasts from the outside. Fig. 2 is a front elevation of the right-hand side of Fig. 1. Fig. 3 is a modification, representing a horizontal and inclined `hearth with both vertical and inclined tuyere-holes for cold, hot, orintensifed hot blast. Fig. 4. is a horizontal section of Fig. 3 below the dotted line c o of said Fig. 3. Fig. 5 is a longitudinal central section, comparatively enlarged, of the water-tuyere for the hot or lintensified blast.

The leading results sought and attained by my present invention are, first, a systematic and infallible process, whereby, at the pleasure 4 or desire of the manager of an ore-reducin g furnace-stack, kiln, or curb, in operation as hereinafter described, either malleable iron, steel, or cast-iron can be produced in any quantities -say from one ton to one hundred tons, or more, daily-and either of the said products at about the same cost. Second, the best construction and .arrangement of the hearth and blast entrances of a furnacestack, kiln, or curb, for the purpose of producing either malleable iron, steel, or cast-iron direct from the ore, at the will of the manager, and either at about the same cost, as before stated. Third, the best construction of a water-tuyerel for either a hot or intensified hot blast.

The efforts heretofore made to produce and run either malleable iron or steel directly from the sloping boshes and contracted hearths of the ore-reducing furnaces in use have resulted in failures as to certainty, quantities, and qualities in relation to the products; and not only has this been the case in respect to malleable iron and steel, but even the cast-iron produced from the same stock and under the 'same conditions of the weather often varies in quality unaceountably,7 and therefore be.

yond the ability of the manager to correct with certainty, because, although he may vary the quality of his cast-iron by varying the burden in the stack-the usual resort-he cannot govern the working of the furnace with certainty, and the products are, therefore, not generally what he hopes or expects.

As the best malleable iron should be as free from carbon as possible, and also entirely free from either sulphur or phosphorus, and unless the carbon which is always present in the reducing-furnace) and the sulphur or phosphorus (either of which, and sometimes both, often present also) are volatilized and driven off by the blast, will combine with the iron, and the result will be an inferior cast-iron.

Without referring to other volatile impurities which will combine with the iron when prevented from being driven off` during the process of reducing the ores, it will be evident that as the partially-fused and agglomerated portion of the stock is pressed upon and confined-by the compacted burden in the tall furnace-stack now in general use, the volatile impurities referred to cannot escape upward, and must, under the intense heat and pressure, combine with themelting iron and produce the objectionable result named.

If in such furnaces it be desired to produce steel direct from ore, free of any sulphur or phosphorus, the specific quantity of carbon necessary to be combined with the iron to produce the steel cannot be properly apportioned in such furnaces, and therefore the result must be a failure, unless otherwise by mere chance.

If any particular grade or quality of castiron be desired, however suitable the ore may be, it cannot be obtained either withv certainty or continuously in such furnaces, because the particular quantity of carbon necessary to be `combined with the iron to produce the said particular quality or grade of cast-iron cannot be commanded.

I will now proceed to describe my process in connection with the apparatus therefor.

The interior of the furnace is formed by walls A, :made vertical on the inside, and a step-like hearth, al, equal in area to the area of the lower end of the interior of the furnace, and sloping downward at about ten degrees from the vertical inside of the wall to the runout opening or channel B, and the risers of the steps perforated with blast-pipe or tuyereholes 2 2, opening about a foot apart from each other, and inclined slightly downward through the wall A and hearth a', so as to prevent the fluid iron from running back into the pipes, and so that the blast of the tuyeres will be driven across the horizontal portions of the steps and thus together produce a blast over nearly every square footnof the surface area of the said hearth. If the interior form of the said furnace be rectangular, the said stepped hearth may be constructed in two step-like inclines, sloping toward each other to the saine channel leading to the run-out.

As a modification of the step-like inclined hearth just described for a horizontally-driven blast, the combination of a horizontal and an inclined hearth, arranged with the one immediately below the other, is represented by Figs. 3 and 4. The horizontal hearth a is equal in surface area to the horizontal area of the lower part of the interior of the furnace, has several vertical run-out or blast-holes, 3 3, through it,

' and is supported by any suitable walls or piers,

which rest upon the inclined hearth a in such a manner that, while an intensified hot blast can be driven through the `main run-out channel or opening B over the surface of the lower hearth al, and up through the vertical holes 3 3 into direct contact with nearly every square foot of the bottom area of the fusing-stock upon the said horizontal hearth a, the iiuid metal will at the same time be permitted to run down through the said holes 3 3 to the lower hearth a, and thence to the outlet B. The channel which conducts the hot blast is extended around through the base walls of the furnace and communicates with tuyere-pipes or openings 4 4, whereby the blast is driven in slightly downward-inclined directions over nearly every square foot of the area of the upper hearth a", and thus the vertical and horizontal blasts operating simultaneously, the whole bottom portion of the stock will be rapidly reduced and run out through the opening B into any suitable gravity-vessel for subsequent treatment and disposal, as described in my former Letters Patent for improvements in the manufacture of iron and apparatus therefor. The dotted lines in Fig. l are intended to merely indicate the relative positions of the channel B and gravity-vessel in one of the forms of a furnace described in said patents. The water-tuyere (see Fig. 5) consists of two hollow cylinders-an outer one, c, and an inner one, d-welded together at the blastdischarging end, so as to produce an annular channel, e, around in the inside of the connecting'ends. The opposite end of the outer cylinder c is connected (steam-tight) to aliat plate, j, through which the inner cylinder d is passed, secured in a steam-tight manner, and continned a short distance beyond, so as to form part of the blast-pipe, over the end of which latter it can be adjusted in the usual manner. Attached in a water-tight manner to the inner side ofthe plate f is another hollow cylinder, which extends along, in an isolated manner, between the cylinder c and the cylinder d, and to the saine length, thus dividing the annular space between the two cylinders c and d into two separate and distinct annular spaces, l and 2, which communicate with each other through the annular channel-like end e. At one side of the outer end of the tuyere a water-pipe, h, passes, in a steam-tight manner, through both the outer cylinder c and the partition-cylinder g, and opens into the inner annular space 1, which is left, as before stated, between the cylinders d and g; and directly opposite to the water-pipe h there is iixed, in a like steam-tight manner, through the outer cylinder c, a like water-pipe, fi, which opens directly into the space 2 left, as before stated, between the cylinders c and g, the spaces 1. and 2 thus forniing a continuous annular water-channel from the pipe h round the inside of the end e of the tuyere to the outlet-pipe t for the passage of water, as indicated by the arrows. rllhe central opening in the tuyere conducts the blast into the furnace. The pipe h introduces the cold water, which under a sufficient head pressure, passes through the annular space 1 to the annular channel e at the fire-end of the tuyere, keeping it cool by continual accessions of cold water coming from the pipe vh and absorbing the heat, and, becoming slightly warmed as it passes the annular chamber, enters the outer annular space 2 and passes out through the pipe t', thus keeping the said tuyere from becomiug'injured, by the extreme heat of the interior of the furnace, in a more reliable and certain manner than any water-tuyere heretofore invented for the purpose.

' The outer cylinder c and inner cylinder d, together with the annular channel e, may be produced together of solid metal by boring the blast-channel and the annular water-space so as to avoid any joints near the fire-.end of the tuyere, and then inserting the dividing-channel g and plate f with the pipes h and t'.

In charging a furnace ofthe usual capacity with a View of producing malleable iron direct from the ore, by my process, the depth of the stock from its surface to the hearth should be from four to six feet. For producing steel the stock should be from six to twelve feet deep; and for producing cast-iron the depth of the stock may be from twelve to fifty feet or more. rlhe proper depth, in either case, will be governed by the fragments of the materials constituting the stock-that is to say, if the fragments be large the depth should be increased, and if sm all or very iine diminished accordingly. In charging the furnace-stack, kiln, or a hearth surrounded by a low curb or plane to make.

malleable iron uniform in quality, let the ironstone (and slag, if needed) be uniform in size, te., and the same with respect to the fuel, that there maybe a similar porosity throughout every portion of the stock for the upward pass ing of the carbon and any other volatile impurities to be eliminated; and if the hearth be either inclined or concave the upper surface of the stock from which the iron is to be produced should be correspondingly inclined or concaveeotherwise, the hearth bein gwide and horizontal and the depth of stock shallow, and either concave, sloped, or convex at its upper surface-the resistance to the escape Aof the carbon through the stock would be proportionately greater in one part than in another, the thicker portion producing steel or steely iron, while the thinner portion would be liquefied, nearly free from carbon, or entirely malleable iron but when the two different products eventually become mingled together under the high heat, the carbon will be uniformly combined with the mass and a steely iron only will result. Therefore,whatever angle the hearth may have, the blast should have access alike to every portion of the said hearth or bottom of the furnace, kiln, or curb of the plane upon which the reduction takes place, and with a capacity to allow the blast to be driven upward alike through every part of the stock, under either a light or strong pressure, the blast being arranged to be chan ged from atmospheric air to superheated steam or other gaseous substances, either cold or hot, and, when. desirable, with some aeriform fluids made intensely hot'to meet the numerous other metals, minerals, or impurities, Snc., that are combined with many of the iron-ores. The temperature of the blast should be under entire control, even to the melting of .malleable iron; and so, also, as to be either concentrated or diffused readily, as circumstances may arise for its use, in part or for the whole surface of the hearth; and there must be an inclined, heated, outletpassage for the liquid iron and scoria, after beingliquefied, to pass off as speedily as practicable into the gravity-vessel before referred to, that the iron may be separated from thek scoria for further manufacture, as described in my former patents. The metallic ore which is to be reduced should be either porous or compact, as may best be suited either to expel the different impurities or to retainv the carbon or substances wanted. 'Most of the disintegration can be done by mechanical means, aided by suitable chemicals. The upper surface of the stock, as before stated, should correspond with the form or inclination of the hearth in order to make the degree of resistance to the upward passage of the blast uniform through the stock, and, whether for the production of iron or steel, the same parallelism should be carefully maintained. For the purpose of exactness on this point, there should be an apparatus or implement at hand to readily apply over the surface of the stock to give to it the parallelism required between the surface and the hearth for steel, but more especially for malleable iron. l

As to cast-iron, the exactness of the said parallelism is not a necessity. For malleable iron, where the outlay of capital is intended to be small, or so that the iron may be reduced at the mines on a plane, or elsewhere without a regular furnace-stack, walls are not needed, except a kind of curb around on the lower part of the hearth to guide the liquid iron and slag into the gravity-vessel. If the same ironstone that is being reduced be piled up around the hearth some two to ten feet thick on the top, (and at the proper height for making the iron,) no injurious eifects will result from the sides falling in toward .the mass which is being reduced, as said mass merely contains the additional quantity of fuel and iiux to reduce it advantageously. By this mode no expense canv arise for repairs, except for the hearth, tuyeres, &c., below.

I claim as my inventionl. The process of volatilizing or expelling the impurities contained in the ore employed in the production of malleable iron vdirect from the said ore, by means of a blast applied through or over every part of the surface of a hearth, in either a furnace-stack, kiln, or on an open plane, the stock being fed so that the superimposed charge is permeable, and volatile substances will be permitted to escape freely upward through the same, the duid malleable iron running out with the slagged impurities, substantially as and for the purpose set forth and described.

2. lhe process of making steel direct from the ore by means of a blast applied through or over the Whole surface of a hearth, (either in a furnace-stack, kiln, or on an open plane,) the said hearth supporting a stock so prepared and. fed as to be more or less permeable to partially smother or retain the carbon, and a1- loW only any specific portion of the same to remain and combine with the reduced iron sufficient to produce steel, substantially as hereinbefore set forth and described.

3. The inclined step-like hearth a. with the tuyere-blast holes 2 2, the vertical form of the inside of the curb or Wall A, in combination with any suitable outlet channel or opening for the fluid metal and slag, substantially as and for the purposes hereinbefore set forth.

4. The double hearth, consisting of the horizontal perforated stock'supportin g portion a, pierced with vertical tuyere-holes, and supported upon Walls or columns resting on the bottom of the diused blast-chamber below, and adapted to serve in the reduction of ore into malleable iron or steel, substantially as hereinbefore set forth and described.

5. A gun-shaped Water-'tuyere, consisting` of the hollow outlet-cylinder c and the hollow inner 'cylinder d, connected together at the re-end of the tuyere by the annular channel e, and at the opposite end of the said tuyere by the plate f, in combination with the intervening hollow cylinder g and the pipes h and z', the said parts being arranged to operate together for the introduction of a blast, as and for the purpose hereinbefore set forth.

JOHN W. MIDDLETON. Witnesses:

BENJ. MomsoN, WM. H. MoRIsoN. 

